foam cutter

I made this foam cutter for work (got paid to woodwork in my garage for a day :). I build weather balloon instruments that require lots of foam insulation to keep things warm at 30 km (100k feet) altitudes. We used to hack out foam parts by hand with a knife, and also had a kludged-together foam cutter that wasn’t very reliable, so things were pretty ugly and difficult to produce. Now we can use this thing sort of like a combination bandsaw (long “blade” we can use for tall foam), router table (we trace the pattern around jigs to cut out fancy shapes), table saw (there’s a rockler fence with t-track), and jointer (you can set the fence close and push crooked foam against it while sliding to “joint” an edge) for foam. I wish the same tool could be used to cut wood! It works with a variac (variable AC voltage source) hooked up to a long piece of steel wire stretched vertically from the table to the upper arm. As the wire gets hot it tends to stretch, so I put a simple spring tensioning system on the top. There’s a little metal collet inserted at the bottom to keep the base table from burning too badly. The fifth picture shows one of the jigs we use to cut out a U shape, along with a jigsaw puzzle for fun (they make good souvenirs for visitors). Overall, this tool has greatly sped up our instrument production and reproducible quality. The whole thing is in a fume hood for safety, as melting foam makes some pretty terrible vapors.

I used red oak (usually two 4/4 pieces laminated) for the upper arm and a frame that holds up a melamine / particle board table. Mostly used pocket hole joinery.